Unfortunately most rechargeable cells are fatter than alkaline. I do recommend Ladda brand from IKEA if you want high quality for good price. You need to check dimensions before buying.
You may be able to bring life back to the batteries inside by draining and recharging over and over at least 6 times. Hook up a 12v bulb to the battery and drain it dead then charge and so on... it may revive the cells. You can use a 9v cell or bench top power supply to charge. Or you can do...
I have a Facon Xbox 360 that has the RGH3 mod. I have tried a USB stick (Fat 32 formatted) with "updflash.bin" file and also a DVD, but I cant get it to update through Xell.
If it matters I originally used Jrunner with a PicoFlasher